The MDRD Study is a NIH nationwide cooperative clinical trial to assess whether diets that are low in protein and phosphorus may retard the rate of progression of chronic renal failure without causing malnutrition. The protocol for this study was developed over a period of approximately one year (Phase I) and has been modified during the pilot study (Phase II). The present application is to enter the last two phases of the study (Phases III and IV), which include the main clinical trial (four years) and one year for data collation and analysis. The details of the protocol will not be described here since they are the same for each competing application, and they are most certainly well known to the reviewer. The specific strengths of this application from Harbor-UCLA Medical Center are the extensive experience of the study team in nutritional problems and dietary management of patients with chronic renal disease. This experience dates back many years and has resulted in many publications concerning the nutritional therapy of chronic renal failure. The other major strength of this application is the demonstrated ability of the investigators to recruit patient volunteers in dietary studies. This application includes letters of intent from seven major hospital centers, in addition to Harbor-UCLA Medical Center, in which the chiefs of the nephrology programs have stated their willingness to refer patient volunteers to the Harbor-UCLA MDRD Study Team. In addition, 11 private practitioners or private practice groups have also indicated their willingness to refer appropriate patients to Harbor-UCLA Medical Center for this study.